Electric power metering device and method

Abstract

The measuring device with electric voltage divider comprises a first measuring resistor connected between a voltage measurement input and a common point, and a second measuring resistor connected between said common point and a reference electric ground. A measurement output is connected to the common point. An outer shielding enclosure surrounds the first and second measuring resistors and is connected to the reference electric ground. An inner capacitive electrode surrounding the first and second measuring resistors is arranged inside said outer shielding enclosure. To improve the phase difference and passband, the device comprises a phase difference compensation circuit connected between said inner capacitive electrode and said common point.

The invention claimed is: 
     
       1. An electrical measuring device having an electric voltage divider, comprising:
 a first measuring resistor connected between a voltage measurement input point and a common point, 
 a second measuring resistor connected between said common point and a reference electrical ground, 
 a measurement output point connected to said common point, 
 an outer shielding enclosure surrounding said first and second measuring resistors and connected to said reference electrical ground, 
 an inner capacitive electrode surrounding said first and second measuring resistors and arranged inside said outer shielding enclosure, and 
 a phase difference compensation circuit connected between said inner capacitive electrode and said common point, wherein the compensation circuit comprises at least one electronic component having a temperature dependent variable electric quantity. 
 
     
     
       2. The device according to  claim 1  wherein the compensation circuit is a two-terminal circuit with two input-output points. 
     
     
       3. The device according to  claim 1  wherein the compensation circuit is a phase lead circuit. 
     
     
       4. The device according to  claim 1  wherein the compensation circuit comprises at least one resistor and one capacitor. 
     
     
       5. The device according to  claim 1  wherein said inner capacitive electrode also surrounds the compensation circuit. 
     
     
       6. The device according to  claim 1  wherein said inner capacitive electrode is connected to a compensation output point, and the compensation circuit is connected between said compensation output point and said measurement output point. 
     
     
       7. The device according to  claim 1  wherein the first measuring resistor has a value of more than 50 megohms. 
     
     
       8. The device according to  claim 1  comprising: a first insulating layer between said outer shielding enclosure and said inner capacitive electrode, and a second insulating layer between said inner capacitive electrode and said first measuring resistor, the first and second insulating layer having substantially identical temperature dependent dielectric characteristics.